Benvolio begs Mercutio to leave the streets of Verona. He warns that it is hot outside, and when people get hot, tempers flare. Benvolio is worried that a fight will break out with the Capulets. Both the Montagues and the Capulets have been warned not to fight. The Prince has declared the death penalty if they fight.
Of course, Mercutio is strong-willed and ready for a fight. Ultimately, that is what costs him his life. He is eager to fight. Mercutio claims Romeo has become weak and submissive. He misunderstands that Romeo is in love. Furthermore, Mercutio does not realize Romeo has just married a Capulet. Of course, knowing this may not have calmed Mercutio into submissiveness. Benvolio seems to be the one with the most sense of the two. He even begs Mercutio to leave town:
BENVOLIO: I’m begging you, good Mercutio, let’s call it a day. It’s hot outside, and the Capulets are wandering around. If we bump into them, we’ll certainly get into a fight. When it’s hot outside, people become angry and hot-blooded.
Benvolio was absolutely on target. Moments later, Mercutio and Tybalt fight and Tybalt kills Mercutio. Of course, he intended his sword for Romeo, but now Mercutio lies dead.
Benvoilo asked them to leave